Thread-controlling mechanism for sewing machines



Aug. 24, I943. F. F. ZEIER 3 8 THREAD-CONTROLLING MECHANISM FOR SEWING MACHINES Filed April 10, 1941 s Shet-Sheet 1 O awe/144100.

' Vafa/ M Aug; 24, 1943. F. F. ZEIER 2,327,338

THREAD-CONTROLLING MECHANISM FOR SEWING MACHINES Filed April 10, 1941 s Sheets-Sheet 2 grwa wfov Aug. 24, 1943. F. F. ZEIER 2,327,838

THREAD-CONTROLLING MECHANISM FOR SEWING MACHINES Filed April 10, 1941 s Sheets-Sheet 3 Federic 366 67 wow/m Patented Aug. 24, 1943 UNITED STATES PATENT OFFICE? THREAD-CONTROLLING MECHANISM FOR SEWING MYACHINES Frederick F. Zeier, Fairfield,on11., assignor to The Singer Manufacturing Company, Elizabeth, N. 5., a corporation of New Jersey Application April 10, 1941, Serial No. 387,869

5 Claims. (01. 11.2-24.6)

This invention relates'to chain-stitch sewing machines, and more particularly to a threadcontrolling mechanism for a thread-carrying looper having loop-seizing and -shedding movements. g

In the production of stitched articles it is desirable when sewing fabrics having inherent extensibility to employ aseam having a corresponding amount of elasticity; so that stretching of the fabric will not result in a fracture of the thread or threads comprising the stitched seam. Also, when sewing fabrics having substantially no inhe'rent extensibility and when a very fine fiat seam is necessary, such for example as in the manufacture of mens shirts, it is desirable to form a seam having comparatively little elasticity. It is common knowledge in the sewing machine art that a two-thread chain-stitch seam will possess inherent elasticity if it is'formed so that the needle-thread-loops', remain relatively long and when concatenated with the looper-thread are folded back and lie against the looper-side of the fabric. Likewise, it is 'well known in the art that a two-thread chain-stitch seam possesses relatively little elasticity when the needle-thread-loops extend beyond the looperside of the fabric only sufliciently far to properly anchor the looper-thread at the bends thereof.

In prior sewing machines the conversion from the elastic seam to the inelastic seam or vice versa was not always possible and inthe machines where the conversion was possible the same could be accomplished only after the threadtensions were readjusted and the customary thread take-up and pull-off elements reset or retimed relative to the movements of the looper. To accomplish this readjustment and retiming a trial-and-error method had to be resorted to in order to obtain the desired result. This is timeconsuming and therefore objectionable.

It is the primary object of the present invention to provide a conveniently adjustable threadc'ontrolling mechanism which in one position of adjustment functions in the production of an elastic chain-stitch seam and, in another position of adjustment, functions in the production of a relatively inelastic chain-stitch seam.

This objective is attained by providing an ad-.

justable thread-controller which in one position of adjustment maintains control of the looperthread throughout substantially the entire stitchforming c'ycle, and in another position of adjustment maintains control of the looper-thread during a'portion only of the'stitch-forming cycle.

The above "and other objects willin part be obvious and will in part be hereinafter more fully disclosed.

In the drawings which show by way of illustration one embodiment of the invention:

Fig. 1 is a front elevational view, partly in section, of a sewing machine embodying the present invention. a

Fig. 2 is an enlarged top plan viewof the for ward portion of the machine-bed with the clothplate removed to expose the mechanisms within the bed. i

Fig. 3 represents a vertical sectional view taken substantially along the line 33, Fig. 1.

Fig. 4 represents a vertical sectional view taken substantially along the line 4-4, Fig. 3; showing the thread-controller in its position to assist in the production ofan elastic seam, the full lines showing the thread-controller arm at the lower end of its stroke and the dotted lines showing the thread-controller arm at the upper end of its stroke.

Fig. 5 represents a vertical sectional View taken longitudinally of the seam, showing the seam produced when the thread-controller is adjusted as illustrated in Fig. 4 i

Fig. 6 is a View similar'to Fig. 4; but with the thread-controller in its position to assist-in the production of an inelastic seam, the full lines showing the thread-controller arm at the lower end of'its stroke and the dotted lines showing the thread-controller arm at the upper end or ineffective position of its stroke. j

Fig. 'lrepresents a View similar to Fig. 5, showing the seam produced when the thread-controller is adjustedas illustrated in Fig. 6.

Referring more in detail to the drawings, the invention is "illustrated as applied to the chainstitch sewing machine forming the subject of my copending application Serial N0."3l6,297, filed Jan. 30, 1940. That portion of the sewing machine shown comprises a bed I from one end of which 7 rises a standard 2 of "an overhanging bracket-arm terminating in a head 3. The bed i is preferably substantially rectangular in; plan view and includes front and rear vertical walls 4 and 5 connected together by two transverse partitions 6 and l. Journaled for rotation in a suitable bearing 8, provided in the transverse partition I is a main-shaft 9 carrying atitsforward end a crank [0 (Fig. 2)- connected through suitable mechanism to a looper-carrier ll mounted for oscillation upona fulcrum shaft 12. Supportedin the looper-carrier H is a pair of thread-carrying loopers l3 adapted to be oscillated in a vertical plane substantially parallel with the line of feed. Threaded through each of the loopers is a looper-thread TL, the complete path of travel of which will be fully described hereinafter.

Cooperating with the loopers I3 is a pair of endwise reciprocatory needles M (Fig. 1) fixed at their upper ends in a needle-clamp [5 carried at the lower end of a needle-bar l6 sustained by the machine-head 3. Threaded through each of the needles M is a needle-thread TN.

The thread-controlling mechanism for the looper-threads TL, best illustrated in Figs. 2 and 3, preferably comprises a stationary depending U-shaped member ll formed in each limb with a pair of thread-eyes or guides l8, one of the limbs being vertically slotted at its upper end, as at Hi, to receive a fastening screw 2!) threaded into a supporting stud 2i fixed by the' setscrew 22 in the wall 4 of the bed I. Extending through a clearance opening 23 in the wall 4 of the machine-bed and adapted to. vibrate between the limbs of the U-shaped member I! is the free end of a thread-controlling arm 24 whose inner end issecured preferably by setscrews 25 in the socket'ed end'of an upwardly inclined lever 26, see Fig. 3. The lever 26 is freely fulcrumed at its lower end upon a relatively short pivot-rod 2'1: fastened byset-screws 28 in a lug 29 integral with the wall 5 of the machine-frame. The inclined lever 26 is oscillated about the pivot-rod 21 by a pitman 30 which at its lower end is bifurcated and pivotally receives the opposite. end-portions of a pin 31- secured by a' set-screw 32 against endwise movement inthelever'26,. and at its upper end embraces an actuating eccentric-33= fast upon the main-shaft 9. As the main-shaft is rotated, the lever 26 is oscillated about the pivot-st-ud 21 through the pitmanw30'and .the'threadcontrolling arm 24 is vibrated between the limbs of the U-shaped member I I in time to properly control the looper-threads-TL.

Thefree end of the thread-controlling; arm is bent into substantially U-shape toprovide two thread-engaging limbs 34 and 35 which are disposed on opposite sides of the longer limb of the stationary U-shaped member I1. Depending'preferably upon the adjustment of the threadecontrolling arm 24 in the upper end of the lever 26, one or both of the thread-engag- 26 the thread-controllingarm25 can be cir-,

cularly adjusted-about its longitudinal axis from the position shown in Fig.4, in which the threadengaging limbs 34, 35 are disposed so that a lineconnecting the thread-engaging surfaces of said limbs forms an angle with a line connecting said looper-thread guides, intothe position shown in Fig. 6, thereby to vary its actionon the looper-threads- Tn.

, When the two thread-engaging limbs 34- and 35 of the thread-controlling arm 24 are adjusted-asshown in Fig. 4, the looper-threads T1. are maintained under control throughout a major portion of each stitch-forming cycle; the thread-engaging limbs being-ineffective on the looper-threads only duringthe relatively: short period of time the loopers l3 are advancing to seize the needle-thread-loops cast out by the ascending needles M. In operation and when the thread-controlling arm 24 is at the lower end of its stroke (shown in full lines in Fig. 4), the thread-engaging limb 34 forms a bight in the looper-threads T1. between the stationary thread-eyes l8 and in so doing takes up all the slack in the looper-threads. As the machine continues to run and looper-thread is required in the formation of the stitch, the thread-engaging limbs 34, 35 are raised from the full line position into the dotted line position (Fig. 4). During the elevation of the limbs 34, 35 looperthread given up by the limb 34 between the thread-eyes I8 is immediately taken up by the limb35. In other words, the looper-thread TL is engaged by the spaced thread-engaging limbs 34, 35 seriatim. This cooperation of the two thread-engaging limbs maintains the looperthreads T1. under asubstantially constant strain.

As'aresult of thetautness of the looper-threads a greater length of needle-thread TN is drawn from the supply perstitch with the consequence that a seam is formed having a considerably greater length of needle-thread than looperthread (see Fig. ,5).

When the thread-controlling arm 24"is adjusted so that its spaced thread-engaginglimbs 34, 35 are positioned as shown in Fig. 6,--i. e,;

the thread-engaging limb 35 is turned into a TL are suchas to result in the production of; a. relatively inelastic stitch, such as illustrated in Fig. 7...

It will be understood that a threadecontroller constructed in accordance with the present invention is desirable for .the reason that it pro vides means conveniently and quickly. adjustable,. whereby a two-thread chain-stitch sewingmachine may be adjusted. to eifect the production of an elasticstitch or an inelastic stitch..

Moreover, a thread-controller is produced which. is simple in construction and susceptible of high speed operation without causing breakage of i the sewing threads.

It is obvious that the invention, as defined in,

1. In combination with a threaded reciproca tory needle and a complemental thread-carrying looper, a thread-controlling mechanism including spaced thread-guides throughwhich the looper-thread passes, a vibratory arm; provided with laterally spacedthread-engaging limbs posit-ioned, tostraddle at least one of' said-threadguides, an oscillating lever pivotally supported at one end and provided at its other end with a socket adapted to receive. said vibrating arm,- 9.

- rotary shaft, meansoperatively connecting; said oscillating lever to said rotary shaft, and means for connecting said vibratory arm in the socket of said oscillating lever for circular adjustment about the longitudinal axis of said arm so that in one position of adjustment both of said threadengaging limbs are efiective on the looper-thread and operate to proportion the looper-thread and the needle-thread to produce an elastic stitch a vibratory arm providedwith laterally spaced thread-engaging limbs positioned to straddle at least one of said thread-guides, a rotary shaft, an upwardly inclined oscillating lever pivotally supported at its lower end beneath the level of the axis of said rotary shaft, an eccentric on said rotary shaft, a pitman operatively connecting the oscillating lever to said eccentric, and means 'adjustably securing said vibratory arm to the upper end of said oscillating lever so that in,

one position of adjustment both of. said threadengaging limbs are eifective on the looper-thread and operate to proportion the looper-thread and the needle-thread to produce an elastic stitch and in another position of adjustment only one of the thread-engaging limbs is effective on the looper-thread and operates to proportion the looper-thread and the needle-thread to produce an inelastic stitch.

3. In a sewing machine, the combination with a frame having a bed formed with a clearance opening therein, a threaded reciprocatory needle and a thread-carrying looper, of a threadcontrolling mechanism including spaced threadguides adjustably mounted on said bed, a substantially horizontal vibratory arm extending through said clearance opening and terminat ing at its exposed end in laterally spaced threadengaging limbspositioned to cooperate with said thread-guides, a rotary shaft journaled in said bed, an upwardly inclined oscillating lever pivotally supported at its lower end beneath the level of the axis of said rotary shaft, means including a pitman connected to said oscillat ing lever for actuation by said rotary shaft, and

means securing said vibratory arm to said oscillating lever for circular adjustment about the longitudinal axis of said arm so that in one position of adjustment both of said thread-engaging limbs are effective on the looper-thread and operate to proportion the looper-thread and the needle-thread to produce an elastic stitch and in another position of adjustment only one of the thread-engaging limbs is effective on the looper-thread and operates to proportion the looper-thread and the needle-thread to produce an inelastic stitch.

4. A thread-controlling mechanism for twothread chain-stitch sewing machines comprising spaced looper-thread guides, and a Vibratory thread-engaging member movable transversely of a line connecting said guides, said threadengaging member including spaced thread-en gaging arms one of which works on the looperthread in the field between said thread-guides and the other of which works on the looperthread outside the field between said guides, the thread-engaging arms being disposed so that a line connecting the thread-engaging surfaces of said arms forms an angle with a line connecting said looper-thread guides.

5. A thread-controlling mechanism for twothread chain-stitch sewing machines comprising spaced looper-thread guides, and a vibratory thread-engaging member movable transversely of a line connecting said guides, said thread- -engaging member including spaced thread-engaging arms one of which works on the looperthread in the field between said thread-guides and the other of which works on the looperthread outside the field between said guides, the thread-engaging arms being disposed so that a plane containing the axes of said thread-engaging arms forms an angle with the line passing through said looper-thread guides.

FREDERICK F. ZEIER. 

